Heat exchange systems



Jan. 14, 1964 1-1. GRIEBSCH 3,117,623

4 HEAT EXCHANGE SYSTEMS Filed Sept. 30, 1959 2 Sheets-Sheet 1 FIG. 4

INVENTOR. Hseaeer 62/5856 Jan. 14, 1964 GRIEBSCH 3,117,623

HEAT EXCHANGE SYSTEMS Filed Sept, 30, 1959 2 Sheets-Sheet 2 O Q 0 I I I I O 0 O a 9 0 B 0 O 0 BOT/)O'DOOIOQG 5 90(A1 O 0 Q Q 9 U G .0

I: 3' I: 6 i H II: l K") H G. 3 INVENTOR.

fizeaier ie/aesah United States Patent 3,117,623 HEAT EXCHANGE SYSTEMS Herbert Griebsch, 'Oherhausen-Sterkrade, Germany, as-

signor to Gutehoifnungshiitte Sterkrade Aktiengesellschaft, Oberhausen (Rhineland), Germany, a German corporation Filed Sept. 30, 1959, Ser. No. 843,444 Claims priority, application Germany Oct. 4, 1958 6 Claims. (Cl. 165163) The present invention relates, in general to novel heat exchange systems and, in particular, to the convection portion of air heaters.

For the passage of one exchange medium. surface heat exchanges often have a plurality of parallel-connected pipes, predominantly in the form of pipe coils, which are connected by their ends to common inlet manifolds and outlet mains. These manifolds and mains usually are drums or boxes of such dimensions that the connecting points of all pipe coils can be fixed with sufficient spacing.

All these connections, which preferably are weld unions, can be fixed in force-fit positions only upon assembly of the heat exchanger at the building site. Thereafter, only the pressure test of the pipe system can be performed. This may necessitate rewelding operations which are just as difiicult to carry out. The same is true of the replacement of individual pipe coils.

It is an object of the present invention to provide means aiming at the elimination of disadvantages encountered in known heat exchange systems.

It is another object of the present invention to provide means facilitating unitary and rapid assembly and disassembly of groups of prefabricated and pressure tested pipes.

It is a further object of the present invention to provide means attaining great improvements in the production, assembly and testing of groups of pipe coils.

It is a still further object of the present invention to provide means affording fast and convenient installation in a common vertical plane of the coils of each heating surface group with the respective manifold and mains, with the ends of the coils connected to the manifold and the main and with the coils arranged in superposition in the longitudinal direction thereof.

The above and other objects of the invention will become further apparent from the following detailed description, reference being made to the accompanying drawings, showing preferred embodiments of the [lilvention.

In the drawings, which illustrate the best modes presently contemplated for carrying out the invention:

FIG. 1 shows schematically a vertical section taken through a heating gas channel having an installed pipe coil system pursuant to the present invention;

FIG. 2 is a sectional view taken on line 22 of FIG. 1;

FIG. 3 is a sectional view taken on line 33 of FIG. 2; and

FIGS. 4, 5 and 6 are fragmentary detail views in the area of the coil connections.

Briefly described, pursuant to the present invention the pipe coils are connected in groups to comparativel small inlet manifolds and outlet mains. Each heating surface group is fabricated in the workshop and pre-tcsted for pressure tightness after which it can be installed and disassembled as a unit.

When installed, the coils of each heating surface group are in a common vertical plane with the respective manifold and main. The ends of the coils are connected to the manifold and main and are distributed in superposed relation in the longitudinal direction thereof. The

end pieces of the coils are connected in forked relation with pairs of coils. The inlet of the heating surface groups is disposed at the upper endv thereof with the outlet approximately centrally of their longitudinal extent.

In the first section, the heating surface groups extend between inlet and outlet in a combined transverse and counter-current and in the last section they extend in a combined transverse and codirectional current referring to the direction of the upward flow of heating gases.

Referring now to FIGS. 1-6 of the drawings in detail, there is shown the flue gas channel 1 of a boiler in which there is installed the heating surface of an heater. Said heating surface comprises a plurality of coils 2. The ends of the coils, outwardly of the gas channel, are connected in groups to common bottle type manifolds or distributors 3 and to mains or collectors 4.

Between the coils and the manifolds or mains there are inserted short pipe end pieces 5 having -a fork-shaped branch 6 on the coil side. Consequently, the number of connecting points thereof, which are distributed in the longitudinal direction of the manifolds and mains, is half the number of the coils.

Where the coils 2 pass into and out of the flue gas channel 1, the channel wall is formed by a tamping composition. This composition surrounds the individual coils in sealing relation and is sealed as a cohering block from the adjacent masonry wall by an intermediate layer, preferably asbestos, while permitting a certain degree of relative movement according to the heat expansions of the coils.

In order to connect as many coils as possible to every manifold or main, the respective pipe end pieces may be arranged in two parallel rows. In this case the pipe end pieces are provided, for the purpose of radial discharge, with a corresponding bulge 7 just before the opening, as best shown in FIGS. 2, 3, 4 and 5.

As shown in FIG. 2 with respect to the manifolds 3, the manifolds and mains may be arranged alternately two laterally offset rows for the purpose of greater spacings. In lieu of the ofiset rows, other arrangements may be provided. For example, there may be provided lateral staggering by groups as shown in FIG. 3 with reference to the mains 4.

The fork-shaped branches 6, at the transition from the pipe end pieces 5 to the coils 2, are preferably directed obliquely relative to the horizontal. When all manifolds 3 and mains 4 are on the same level and the respective pipe end pieces 5 are accordingly arranged not only in vertical but also in horizontal rows, there results, as shown in FIG. 6, an alternately mutual staggering of the adjacent coils 2, in the transverse direction of channel 1, in the sense of a perfectly or substantially uniform pipe grid. This pipe grid, with a total cross section given by the number of all parallel-connected coils, extends over the entire coil length.

To provide high efficiency for such an air heater, it is preferable, in addition to the above-mentioned measures, to arrange the coils 2 as shown in FIG. 1. As shown, the coils extend from the manifolds 3, which are disposed very high at the inlet end, in several serpentine configurations, downwardly to about mid-height, then along one channel wall It} to the very bottom, and thence in reverse direction in corresponding serpentine configurations upwardly to the mains 4 disposed at the outlet end.

In this Way there occurs in the first section of the coils, between the air to be heated in the interior of the coils on the one hand and the heat-transmitting flue gases ascending through channel 1, a combined transverse and counter-current and, in the second section of the coil length, a combined transverse and codirectional current. The entering air thus comes in contact first with flue gases having a temperature which has been lowered by the preceding heat transfer, and then, as it is being heated, with correspondingly hotter flue gases. What is exposed to the highest flue gas temperature of this channel, however, is not the outlet end, but a section of the coils located forwardly by approximately one third of the total length.

Consequently, in the zone of the lowest serpentine configuration, there is a particularly large temperature gradient and hence a correspondingly large heat transfer between the flue gases and the air.

The shift of the outlet end of coils 2 into a zone or area of the flue gas channel 1, wherein the flue gaseis have previously yielded some heat, has been effected for the protection of the coils in order that they will not be exposed there to the highest temperatures of both heat exchange media internally, as well as externally.

This has no adverse eifect on the total efiiciency b cause the somewhat smaller heat transfer in the last coil section, according to the respective temperature gradient, is compensated by the larger heat transfer in the preceding coil section. At any rate, the flue gas temperature is still sufliciently higher, in the end zone also of the coils, than the air temperature prevailing there.

Moreover, every coil is assembled, preferably by welding, from several sections of diiferent quality material such as steel alloys, which are adapted to the different thermal stresses in accordance with the flue gas temperatures decreasing in upward direction in channel 1.

In conventional manner, vertical pipes 8 serve to secure the coils 2 within channel 1. Pipes 8 are suspended at the upper end by members (not shown) and, in addition, are utilized as additional heating surface by connection to the manifolds 3 and mains 4. In the zone or area of the highest flue gas temperatures of this channel, i.e., at the very bottom, branches 8' of the securing pipes are provided in the form of blind pipes. 'In lieu thereof, rod-shaped securing members may be used.

The securing pipes '8, 8 are passed, as best shown in FIGS. 3 and 6, between pairs of 'coils belonging to the same pipe end pieces 5, beingrsecured to them by shackles, or the like, in every horizontal course, with the exception of a single one, for example, the second from the bottom.

A particular advantage of this model is the easier production 'of the individual coil groups or registers, Whose connections with the pipe end pieces and with the manifolds and mains can be made in advance in the workshop. All welding seams, as well as subsequent testing for pressure tightness, can be performed more conveniently in the workshop than at the building site. In addition, the installation of such finished registers is much easier than if every coil must be individually assenibled, readjusted, welded, and secured. Moreover, when replacing defective parts, it is not necessary to cut ofi? individual pipes and to weld them on again, but simply whole cohering structural groupsare taken out and reinstalled;

In lieu of air and flue gases, other heat exchange media may be used.

Various changes and modifications may be made without departing from the spirit and scope of the present invention and it is intended that such obvious changes and modifications be embraced by the annexed claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

'1, In a convection heat exchange apparatus, wall means defining an elongated vertically extending flow chamber adapted to provide an ascending fluid flow passage therethrough, a plurality of meander-shaped tube coils extending through said chamber, each of said meander-shaped tube coils defining a fluid flow path therein, said plurality of meander-shaped tube coils being divided into several groups, each of said groups of tube coils being connected to one inlet man fold and one outlet manifold, said inlet manifold being disposed at the upper end of the longitudinal extent of a respective group of tube coils and said outlet manifold being disposed approximately midway between the upper and lower ends of the longitudinal extent of said same group of tube coils, both manifolds of each group of tube coils being disposed in a common vertical plane with their respective group, each of said plurality of meander-shaped tube coils being constructed to provide a first tube portion extending from said inlet manifold for substantially transverse and upstream fluid flow with respect to the direction of flow in sm'd flow chamber, and a second tube portion for substantially transverse and downstream flow with respect to the direction of flow in said flow chamber.

2. In a convection heat exchange apparatus as set forth in claim 1 wherein end pieces respectively connect said coils to said inlet and outlet manifolds, said end pieces being in superposed relation in the longitudinal direction thereof, and fork-shaped branches connecting the end pieces with pairs of said coils.

3. In a convection heat exchange apparatus as set forth in claim 2, wherein the coil end pieces each have a bulge in the direction of radial discharge and two rows of coil end pieces are connected to each manifold, each said forked branch being disposed obliquely relative to the horizontal, so that pairs of adjacent coils connected to the same end pieces are staggered in height in relation to each other.

4. In a convection heat exchange apparatus as set forth in claim 1, including a plurality of vertical securing pipes, said coil groups being suspended from said securing pipes.

5. In a convection heat exchange apparatus as set forth in claim 1, wherein the manifolds of the individual tube coil groups are alternately in laterally staggered relation to each other.

6. In a convection heat exchange apparatus according to claim 1, including a plurality of vertical securing pipes, said securing pipes being inserted between adjacent groups of tube coils, said groups of tube coils including horizontal sections which are secured to said vertical securing pipes.

References (Iited in the tile of this patent UNITED STATES PATENTS 1,786,909 Jackson et al Dec. 30, 1930 1,826,411 Bellamy et al. Oct. 6, 1931 2,211,724 Kerr Aug. 13, 1940 2,328,039 Toorney et al Aug. 31, 1943 2,798,464 Seidl July 9, 1957 2,851,017 Blaskowski Sept. 9, 1958 2,869,518 Seidl et al. Jan. 20, 1959 2,880,973 Langvand Apr. 4, '1959 2,902,982 Reward et al. Sept. 8, 1959 2,916,263 Godshalk Dec. 8,1959 2,921,565 Koch Ian. 19, 1960 FOREIGN PATENTS 9 550,289 Belgium Feb. 13, 1957 903,630 France Ian. 29, 1945 

1. IN A CONVECTION HEAT EXCHANGE APPARATUS, WALL MEANS DEFINING AN ELONGATED VERTICALLY EXTENDING FLOW CHAMBER ADAPTED TO PROVIDE AN ASCENDING FLUID FLOW PASSAGE THERETHROUGH, A PLURALITY OF MEANDER-SHAPED TUBE COILS EXTENDING THROUGH SAID CHAMBER, EACH OF SAID MEANDER-SHAPED TUBE COILS DEFINING A FLUID FLOW PATH THEREIN, SAID PLURALITY OF MEANDER-SHAPED TUBE COILS BEING DIVIDED INTO SEVERAL GROUPS, EACH OF SAID GROUPS OF TUBE COILS BEING CONNECTED TO ONE INLET MANIFOLD AND ONE OUTLET MANIFOLD, SAID INLET MANIFOLD BEING DISPOSED AT THE UPPER END OF THE LONGITUDINAL EXTENT OF A RESPECTIVE GROUP OF TUBE COILS AND SAID OUTLET MANIFOLD BEING DISPOSED APPROXIMATELY MIDWAY BETWEEN THE UPPER AND LOWER ENDS OF THE LONGITUDINAL EXTENT OF SAID SAME GROUP OF TUBE COILS, BOTH MANIFOLDS OF EACH GROUP OF TUBE COILS BEING DISPOSED IN A COMMON VERTICAL PLANE WITH THEIR RESPECTIVE GROUP, EACH OF SAID PLURALITY OF MEANDER-SHAPED TUBE COILS BEING CONSTRUCTED TO PROVIDE A FIRST TUBE PORTION EXTENDING FROM SAID INLET MANIFOLD FOR SUBSTANTIALLY TRANSVERSE AND UPSTREAM FLUID FLOW WITH RESPECT TO THE DIRECTION OF FLOW IN SAID FLOW CHAMBER, AND A SECOND TUBE PORTION FOR SUBSTANTIALLY TRANSVERSE AND DOWNSTREAM FLOW WITH RESPECT TO THE DIRECTION OF FLOW IN SAID FLOW CHAMBER. 